1. Field of the Invention
The present invention relates to the field of labeling machines, and more particularly, to a relatively compact labeling machine and method incorporating the use of a suction plate assembly and air piston to control the advancement and continuous application of pressure sensitive labels from a carrier web onto containers.
2. Description of the Related Art
The prior art relating to pressure sensitive labeling devices includes a variety of specialized machines comprising differing means of applying labels to bottles or containers. Pressure sensitive labels are typically secured to one side of a non-adhesive label carrier web that is rolled into a dispensing reel. The pressure sensitive labels are evenly spaced along the label carrier web and can be peeled off the web with appropriate mechanical manipulation of the carrier web.
A device or apparatus used to continuously apply pressure sensitive labels to bottles or containers that travel along a conveyor must control numerous dynamic variables as necessary to automatically place and secure the labels onto the passing bottles or containers. These dynamic variables include dispensing the label carrier web, timing the advancement of the labels to the passing containers, separating the labels from the carrier web and securing the labels onto the container. It is crucial that both the timed advancement and placement of the label carrier web be carefully controlled and monitored so that the labels are precisely advanced and accurately placed upon the container. Typically, the label carrier web is advanced and controlled by running the carrier web through a series of tension rollers intended to keep the carrier web from slipping or sliding. A mechanical clutching device is used to engage and disengage a driving roller according to the necessary advancement of the carrier web. A serious disadvantage of using mechanical clutching devices with labeling machines is the mechanical wear experienced over time and the need to adjust and tune the clutching operation.
Most pressure sensitive label machines differ from each other in the method in which the labels are removed and placed upon the moving bottle or container. Most devices that incorporate the use of negative pressure use suction to lift the label off the carrier web and place the adhesive side of the label to the container or bottle. This may be accomplished by a rotating vacuum drum or a vacuum swivel arm.
An example of a vacuum drum device is U.S. Pat. No. 5,256,239 to Voltmer et al. described as a continuously moving web pressure-sensitive labeler for applying labels to containers. The device comprises a label applying means for stripping labels from the moving web and delivering the stripped labels to containers as they pass a label applying station. The label applying means includes the use of a rotating vacuum drum that strips the pressure sensitive label from the web by pulling the non-adhesive side of the label onto the drum after which the drum rotates and applies the adhesive side of the label to the passing container.
U.S. Pat. No. 5,061,334 to Paules is described as a machine and method for high speed, precisely registered label application with sprockets for positioning the label on a transfer wheel. This apparatus has a similar application means as the Voltmer et al. invention described above in that there is a vacuum drum used to peel the labels off the web and then apply the pressure sensitive label to a container.
A distinct use of a vacuum device is disclosed in U.S. Pat. No. 3,984,279 to Bohdan Wolodymyr Siryi which is a labeling apparatus that uses a vacuum label head that pivots on a pivot joint. The vacuum pivot head removes the non-adhesive side of the label from the carrier web and then applies the label to the surface of a container. The head incorporates a plug that is arranged to move out of a gas tight position upon contact with the label to allow application of the label to the container.
Although the present invention employs the use of a vacuum, the application of a vacuum and control of the carrier web is distinct from the prior art. A double sided suction plate assembly is used in the present invention to lightly hold the non-label side of the label carrier web to a front and rear face plate of the suction plate assembly. The suction provides sufficient tension on the label web carrier to properly control and regulate both the advancement of the carrier web and placement of the labels onto passing containers. In this way, no vacuum is used to directly manipulate the labels themselves from the label web carrier and then onto a passing container. Instead, the suction plate assembly obviates the need for multiple tension rollers to create the necessary carrier web tension to properly control the label carrier web.
The present invention replaces the mechanical clutch engaging mechanism common in the prior art with a pinch roller assembly that advances the carrier web by periodically pinching the carrier web between a pinch roller and a constant rotating pressure roller. The pinch roller is engaged when a passing container or bottle triggers a catch switch activating the pneumatic piston to push the pinch roller lever against the rotating pressure roller. This action advances the carrier web so that a label may be applied onto the passing container at the label applicator station.